collect all tags without repeat from current dir wd14 files in output file

process.js

var fs = require('fs');
const path = require('path');

const UTF8 = 'utf8';
const EXTENSION = '.wd14';
const OUTPUT_FILE = 'words.txt';
const EMPTY_STRING = '';
const NEW_LINE_SEPARATOR = '\n';
const COMA_SEPARATOR = ',';
const COMA_SPACE_SEPARATOR = ', ';

async function readFile(filePath) {
    try {
        return await fs.promises.readFile(filePath, UTF8);
    } catch (err) {
        return false;
    }
}

async function writeFile(filename, writedata) {
    try {
        await fs.writeFileSync(filename, writedata, UTF8);
        return true;
    } catch (err) {
        return false;
    }
}

const words = new Set();
fs.readdir(process.cwd(), (err, files) => {
    files.filter((file) => path.extname(file) === EXTENSION).forEach(file => {
        readFile(file).then(data => {
            if (data) {
                data.split(NEW_LINE_SEPARATOR).forEach(line => {
                    line.split(COMA_SEPARATOR).forEach(word => {
                        if (word.trim() !== EMPTY_STRING) {
                            words.add(word.trim());
                        }
                    })
                });
            }
            writeFile(OUTPUT_FILE, Array.from(words).join(COMA_SPACE_SEPARATOR)).then(result => {
                console.log(OUTPUT_FILE, result);
            });
        }).catch(err => {
            console.error(err);
        })
    });
});